1. Field of the Invention
One embodiment of the present invention relates to a memory device which includes a transistor including an oxide semiconductor, and a method for driving the memory device.
Note that one embodiment of the present invention is not limited to the above technical field. The technical field of one embodiment of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. In addition, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter. Specifically, examples of the technical field of one embodiment of the present invention disclosed in this specification include a semiconductor device, a display device, a liquid crystal display device, a light-emitting device, a lighting device, a power storage device, a memory device, a method for driving any of them, and a method for manufacturing any of them.
2. Description of the Related Art
A semiconductor device that can hold data even after power supply is stopped by using a transistor including semiconductor silicon (Si) in its channel formation region (such a transistor is referred to as a Si transistor in the following description) and a transistor including an oxide semiconductor (e.g., an oxide including In, Ga, and Zn) in its channel formation region in combination, has attracted attention (see Patent Document 1).
In recent years, with the increase in the amount of data manipulated, a semiconductor device having a larger storage capacity has been required. In such situations, the semiconductor device disclosed in Patent Document 1 has a structure in which multilevel data is stored and read.